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Good/bad diode.

T

Taylor21990

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Oct 30, 2019
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How can I tell if I have a bad diode(really dim) or a bad driver. (X drive 1.8A.) I'd show a pic but it won't let me. Every time this happens. Whether it's with an lm317, or the X Drive. Getting really frustrating.
 





Well, there are many reasons you could be having these problems. Without having the proper test equipment to run a driver without a laser diode attached or testing a laser diode without using a driver you may never find out. If you buy all your parts assembled from DTR you can get a tested diode with driver and lens in a module that should work fine without having any test equipment at all. But, you will pay a higher price than you might otherwise. It is a compromise that you may have to make in order to get a working module. I buy modules from DTR as his are the best for my purposes, but I often buy my diodes from other sellers. I have bought the same diode, even unused M140 diodes in the past with no solder or short pins, but had to buy at least five to get them for $40.00 each. They can now be had for much less than that as they are no longer used much in new equipment that can be harvested. So, I guess buying from DTR is your best bet for getting working modules ready to drop into a host and only needing to solder two wires together.
 
I’m feeling to lazy to answer. Search for laser diode dummy load
 
paul1598419 said:
Well, there are many reasons you could be having these problems. Without having the proper test equipment to run a driver without a laser diode attached or testing a laser diode without using a driver you may never find out. If you buy all your parts assembled from DTR you can get a tested diode with driver and lens in a module that should work fine without having any test equipment at all. But, you will pay a higher price than you might otherwise. It is a compromise that you may have to make in order to get a working module. I buy modules from DTR as his are the best for my purposes, but I often buy my diodes from other sellers. I have bought the same diode, even unused M140 diodes in the past with no solder or short pins, but had to buy at least five to get them for $40.00 each. They can now be had for much less than that as they are no longer used much in new equipment that can be harvested. So, I guess buying from DTR is your best bet for getting working modules ready to drop into a host and only needing to solder two wires together.
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K thanks. Just really want to put my own together. Guess I'll just buy the proper test equipment.
 
paul1598419 said:
Well, there are many reasons you could be having these problems. Without having the proper test equipment to run a driver without a laser diode attached or testing a laser diode without using a driver you may never find out. If you buy all your parts assembled from DTR you can get a tested diode with driver and lens in a module that should work fine without having any test equipment at all. But, you will pay a higher price than you might otherwise. It is a compromise that you may have to make in order to get a working module. I buy modules from DTR as his are the best for my purposes, but I often buy my diodes from other sellers. I have bought the same diode, even unused M140 diodes in the past with no solder or short pins, but had to buy at least five to get them for $40.00 each. They can now be had for much less than that as they are no longer used much in new equipment that can be harvested. So, I guess buying from DTR is your best bet for getting working modules ready to drop into a host and only needing to solder two wires together.
Click to expand...
Thank you for the reply. Off topic, but I have the osram pl520 50mw diode. Any suggestions on a good driver? Or maybe what resistor to put across the lm317? I read somewhere it's 1.25 divided by the desired current.
 
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I have run that particular diode off of two li-ion batteries without a driver and it didn't die, if it either gets too hot or is driven too hard the output will get lower and lower and recover after the voltage is removed and put back on. This however is abusing the diode and will likely result in reduced life. That said, you could just hook up the nominal voltage the manufacturer specifications call for to test it without a constant current driver, as long as it is heat sinked, if only for a moment, and I wouldn't be afraid of destroying it, given I've run more than one of these for long periods of time without a driver and no failure yet.... Still, it is abusing the diode.

Of course, if you try it, the diode will fail the first try, that's how these things usually go.
 
Alaskan said:
I have run that particular diode off of two li-ion batteries without a driver and it didn't die, if it either gets too hot or is driven too hard the output will get lower and lower and recover after the voltage is removed and put back on. This however is abusing the diode and will likely result in reduced life. That said, you could just hook up the nominal voltage the manufacturer specifications call for to test it without a constant current driver, as long as it is heat sinked, if only for a moment, and I wouldn't be afraid of destroying it, given I've run more than one of these for long periods of time without a driver and no failure yet.... Still, it is abusing the diode.

Of course, if you try it, the diode will fail the first try, that's how these things usually go.
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Thank you. Very informative! Will it be at it's utmost brightness as well? Or does a driver have to be used? Testing wise only for a second or less
 
Yes, it will actually be at more output than usual, 75-100 mw which also reduces the life, but when rated for thousands of hours of run time and we only use it for hundreds in a pointer, then maybe acceptable. Anyone here will tell you to use a driver, it's needed, but I'm reckless and that particular diode has survived mistreatment for me. It is the only diode I've dared do that to, I'd only do it if you don't care about an early failure as it will likely die early, but if just for a few moments (if heat sinked enough), I don't think it will reduce the life. No way to guarantee that though.
 
Alaskan said:
Yes, it will actually be at more output than usual, 75-100 mw which also reduces the life, but when rated for thousands of hours of run time and we only use it for hundreds in a pointer, then maybe acceptable. Anyone here will tell you to use a driver, it's needed, but I'm reckless and that particular diode has survived mistreatment for me. It is the only diode I've dared do that to, I'd only do it if you don't care about an early failure as it will likely die early, but if just for a few moments (if heat sinked enough), I don't think it will reduce the life. No way to guarantee that though.
Click to expand...
I won't blame ya if mine fails. Like I said I only want to test it. They're only 20 bucks too so that's nice. I'll look into building or buying a proper driver. Ty!
 
Why quote every response when no one else is posting between us in this thread? Seems like a waste of thread space to me, but then, so is my signature.
 
I hid all signatures a long time ago, cleans things up a lot.
 
Edit: Just went into preferences and unchecked it, so I won't see them now either.
 
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